


Drowning on Air

by Catsitta



Category: Undertale (Video Game)
Genre: Angst, Bittersweet Ending, But WHO?, Character Death, Cuddles, Falling In Love, Fellswap Papyrus (Undertale) - Freeform, Fellswap Sans (Undertale) - Freeform, Fluff, Fluffyhoodies, Human!US!Papyrus, I swear there is a lot less bad times in this fic that the tags make it seem, Implied/Referenced Character Death, Injury Recovery, Light LazyBerry, Love after Loss, M/M, Mating Rituals, Mermaids, Multiship, One-Sided Attraction, One-Sided Relationship, One-sided Kustard, One-sided RottenBerry, Past Abuse, Permanent Injury, Pining, Probably some ethics issues, Romance, Sans (Undertale) Has Issues, Skeleton Mermaids, Swearing, Swearing tag is mostly Red's mouth, Terminal Illnesses, These pairings are all over the place but make sense when you read, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Papyrus (Undertale), Underswap Sans (Undertale), edgeberry, eventual poly - Freeform, rottenjoke - Freeform
Language: English
Status: Completed
Published: 2019-11-27
Updated: 2019-12-09
Packaged: 2021-02-26 03:54:48
Rating: Mature
Warnings: Major Character Death
Chapters: 7
Words: 15,409
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21587200
Author URL: https://archiveofourown.org/users/Catsitta/pseuds/Catsitta
Summary: He was unlikely to survive the night with his injuries. Even if he did, the mer would never be fit to return to the sea from which he was stolen. For Sans, dusting was preferable, it was what monsters did when they lost all reason to Hope. Too bad the Rehabilitation Center had a history of rescuing mers like him.Shortfic | Mermaids | MultiShip
Relationships: Papyrus/Sans (Undertale), Sans/Sans (Undertale)
Comments: 124
Kudos: 216





	1. It's not water in my lungs

**Author's Note:**

> This fic is actually complete! I'll be adding chapters as I edit them~ 
> 
> Rating is for sensitive/mature themes.

_“Just hang on. We’re going to do everything we can to—”_

Humans. Sans was being manhandled by humans. 

_“—He’s fading fast! We need to stop his bleeding now—”_

Why couldn’t they just let him be? Let him die in peace with what little dignity he had left. They just had to keep making him suffer, as if killing his brother, and stealing him from the seas to torture him just wasn’t enough. 

_“—C’mon little guy. You can’t give up now. You’re safe. You just have to—”_

Stay Determined? Why? To give humans further opportunities to maim him? If they really cared, they would dump him into the waves to crumble into dust and return to the seafoam from which his kind were Born. 

_“—his stats. He’s at less than one—”_

Unwilling to dredge up the willpower to open heavy sockets, Sans laid pliant, unresisting, unseeing, as his so-called rescuers kept shouting at him to stay alive. A dozen hands poked and pulled at his tail, his ribs, his skull, until once more pain overcame all other sensation. He felt his Soul stutter. Always so weak and fragile, a pulsing bubble caged behind bone instead of resilient pearl cupped by an oyster. _AndThenTheyWereTouchingIt._

_“—won’t survive the night if we don’t—”_

He knew nothing more.

Then he woke.

He wasn’t supposed to wake.

Maybe if he didn’t open his sockets...he’d eventually fall asleep forever.

Too bad the humans were so noisy. It made it hard to sleep when they. Just. wouldn’t. stop. talking. 

“His stats aren’t improving. He stabilized at one HP last night and we can’t coax him into eating. Or swimming. We put him in the recovery tank when he woke up, but then we had to have a diver go in and pull him to the surface when he wouldn’t come up for air.”

“You can’t save’em all Rus. He was in a bad way when the team brought him in. The fact that he didn’t dust in surgery is a miracle in itself.”

“But Dyne! He’s lived through so much. We can’t give up on him now.”

“He has to WANT to live, rookie.”

“Then we’ll just have to give him a reason.”

“What are you—? HEY! Get back here, Punk!”

His traitorous Soul kept beating. Clinging to survival like a barnacle on the hull of a ship. The humans submerged him water. It tasted of salt. They kept touching him. And touching him. Eventually, they stranded him in the surface of this false ocean, keeping him afloat so that he didn’t suffocate below. Because while he could breathe some underwater, not unlike a fish; akin to whales, he needed air to help keep mana flowing through his system. 

“I hope you know what you’re doing…”

“Trust me, Dyne. You said it yourself that Red perked up when you put Crimson in the recovery tank with him. Mers need social bonds.”

“Yeah, but Crimson and Red are from the same school! And Crimson was an utter nightmare that kept trying to kill people whenever he was conscious until he was reunited with Red.”

“The new guy isn’t in any shape to do any murdering, and judging by his teeth, he isn’t a consummate carnivore like those two. Him and Blue should get along well enough. Besides, Blue loves working with any new perma residents.”

“This is a bad idea…”

“Hey. Who’s the expert here?”

“Pfft. That fancy piece of paper don’t make you an expert, punk.”

“No, my work with Blue does.”

“Hnnnnng. WHATEVER. If this new Mer hurts Blue, it’s your head.”

Just stop. Stop talking!

Sans felt it before he heard it. The overexcited hum of a monster Soul. A land dweller that worked with the humans? There was more chatter, more words he wanted to drown out so he could sleep, and then, the water shifted. The monster was swimming towards him, its Soul bright. So bright. He didn’t even need to look at it to know it burned like dawn after storm ridden night, utterly bubbling with energy. (Like him. Like his brother. The only creature he had left in this miserable world before it decided he didn’t deserve even that scrap of happiness.) 

“HELLO!”

It—he—spoke like his brother too. The pitch of his voice was different and accented softly, just enough that Sans didn’t force open his sockets just to confirm that this was all a terrible dream. 

“I WAS TOLD YOU NEEDED A FRIEND. I, THE MAGNIFICENT BLUE, AM HERE TO ASSIST IN YOUR RECOVERY! MWEH HEH!”

Blue. Didn’t the humans talk about a Blue? Another mer?

Hands—small and skeletal—whisked down the elongated ridges of his spine, picking between vertebrae in an act that was wholly too intimate to be allowed of a stranger. A growl built low in his non-existent throat. Blue clicked his teeth in return, calling Sans’ bluff. He dug a finger between tender bones and crooned upon fishing out the Sand grime that built up there, left neglected by Sans, and without a fellow mer to groom away. Sans grumbled as the stranger took liberties, as if they were schoolmates mingling before sleep, but his protests steadily fell silent as Blue mercilessly, and diligently, chased away the dinginess that Sans allowed to collect since he was captured.

Blue was just as noisy as the humans. He didn’t even need a response from Sans to continue chattering. But intermixed with the continuous blabbering were clicks, whistles and hums. He even offered a song that was startlingly gentle. Wasn’t this other mer tired of his unresponsiveness? Why did he keep touching? Keep grooming? He shivered as lush tail flukes whispered along his flank. Blue wasn’t a large mer, perhaps Sans’ size judging by the tail that kept brushing against his own. 

It was sudden enough to notice when Blue swam off, leaving Sans adrift in the contraption the humans forced him into. He instinctively tried flicking his tail, as if to float back into the company of his unwanted (needed) friend in this nightmare. But the motion left him clenching his teeth against a bolt of pain, and he went limp, exhausted as soon as the wave passed. Next thing he knew, Blue was back upon him again, like a seahorse in need of anchoring, the pungent smell of shellfish flooding his nasal passage. “I THOUGHT YOU MIGHT LIKE THIS TO EAT!” Sans tilted his head away. “OH DON’T BE SILLY, I FELT THAT SURGE OF MAGIC. I WOULD BET ALL THE PEARLS IN THE OCEAN THAT YOU’RE HUNGRY.”

Blue fumbled with his face, his teeth, as if he wasn’t afraid Sans would bite him for his audacity. Such a rude little mer. No manners. Sans bared his fangs, but Blue took advantage of the tiniest gap between his teeth and shoved a chunk of crab meat into his mouth. Instantly, his own magic reacted to the long denied nourishment, sparking into shape, devouring the crab until all that remained was the tongue his body formed in response to a meal. Blue kept poking at his face. Sans found his willpower crumbling. He opened his mouth, feeling like a helpless pup in need of his mother’s fussing.

It was days later before Sans dared let his sockets open. His death denied to him by humans and an overly affectionate mer. A single eyelight flickered into existence. Weak and hazy around the edges. He focused on his empty right socket. There was magic there still. With a little focus, he formed another eyelight. He’d never see out of that socket again after what happened (glinting metal, child-like laughter, painpainpain), but he could at least pretend he wasn’t as broken. For the first time, he looked at his new prison. He had to be in some kind of aquarium (a word he picked up from them) though the occupants he could spy in the tanks were generally few and sickly. An aquarium of broken things?

There were no humans milling about, but it was far from quiet, the roar and hum of their gadgetry a numbing symphony in the dark. Sans pawed ineffectively at the brightly colored contraption the humans left him floating in so that he didn’t accidentally drown. Heh. How kind of them. 

“YOU’RE AWAKE!”

Sans blinked at Blue, who, apparently noticing his movement, decided to surface. Once more he was touching Sans. So much touching. Hands found either side of Sans’ skull and he gasped, forcing their brows to almost touch. Oh...okay. Sans was not expecting Blue’s eyelights to be blown out so large, like glowing jellies trapped in a cave, radiant and alluring to the wayward traveler. Maybe his school didn’t use their eyelights to communicate their emotions and intentions like Sans’; hopefully, because he wasn’t sure how he felt about this overly affectionate mer actually courting him. Especially since he was, well, still on the cusp of dying.

Blue pushed away with a giddy noise, giving Sans a look at his ectoflesh. It was a brilliant cyan, tail perfectly formed, flukes flawless. There wasn’t a mark or scratch upon those bones or a streak of discoloration tainting his magic. Unlike...Sans dared a look down, the flotation device blocking sight of the injuries he knew marred him. From the mess that was his ruined sternum and ribcage, to what he feared had become of his tail. Did he have fins down there anymore? Normal damage wouldn’t maim him forever, such as shark teeth, but a human slowly and methodically carving bits off of him while he screamed for mercy…

It was trauma that scarred monsters; crippled them in the rare instances they survived.

(Maybe he should be thankful his brother died so quickly. It was better Sans was the one captured.)

Blue popped back up weilding a crab. A live crab. Legs flailed and claws snapped as the creature protested being plucked up from the bottom of the tank. “ARE YOU HUNGRY? RUS ALWAYS MAKES ME CATCH MY FOOD INSTEAD OF GIVING ME PREPPED STUFF. SAYS IT’S GOOD FOR PROBLEM SOLVING ENRICHMENT. I THINK IT’S JUST AN ATTEMPT TO SEE IF I’LL GET TIRED IF I SPEND HALF THE DAY CHASING AROUND TINY FISH OR CRACKING OPEN SHELLFISH.” Seemingly unbothered by the fact that Sans had yet to speak, he formed a sharpened bone and cracked open the crab. (Blue sounded so much like the humans. Maybe he didn’t think that Sans understood him and was talking aloud for his own benefit. How long had he been here to abandon most of his native tongue from his school?) With a little fiddling, he pried out the fresh meat and held it to Sans’ teeth as if he were a pup that didn’t understand what food was until someone shoved it into his mouth for the first time.

Sans growled.

“WHAT? YOU NEED TO EAT. UNLESS YOU FEEL UP TO DE-SHELLING YOUR OWN MEAL..” He waved a leg at Sans, who made a grab for it. Blue paused. “OH! IS THAT IT?” He laid the leg in Sans’ hand and watched him make a pitiful attempt at cracking it. Sans slumped against his flotation device, exhausted so easily. Blue tsked and pressed the meat to his teeth again, in a manner that was utterly mothering. And Sans did what he did best lately. He gave up. Just opened his teeth and let the manner mer feed him.

“Hey little guy, Blue says you’re feeling better.”

Sans hissed. It was an embarrassingly petulant noise. Perched at the edge of the tank was the human called Rus, his complexion pallid, eyes brown, and hair the color of coarse sand. He looked nothing like them, far taller and angular in frame, and stinking of something acrid. 

“Heh. Don’t blame you for being skittish. You’ve gone through a lot. Hoping that, at the very least, you might not hate me someday.” There was definite intelligence in those eyes, and his Soul wasn’t...threatening. Sans let some of his recovering magic pool behind his working eye, the false pupil widening, flickering just a flash, before vanishing. Rus inhaled sharply. “Spunky, aint’cha? Guessin’ that was a warning to stay out of your turf, yeah?” He stood up. “Dunno how much you understand me, but I think it’s more than you let on. I’ll be back, buddy.” And with that, he climbed down, leaving Sans with his thoughts.

Rus’ Soul wasn’t a terrifying Red. But instead, it was the same shade of cyan as Blue’s tail. Patience. And maybe, despite his pushiness, the color suited the mer the way it did the human. It was a color that didn’t haunt him.

Speaking of whom...Blue splashed up, “HOW DO YOU LIKE, RUS? HE’S NICE. KINDA LAZY AND WON’T STOP SMOKING EVEN THOUGH IT SMELLS SO BAD THAT IT CAN’T BE GOOD FOR HIM. BUT NICE.” 

Sans stared at Blue for a long moment before giving a small, indifferent shrug.

Blue’s eyelights, impossibly, grew larger, and he went back to his usual babble.

He supposed he didn’t mind the endless talking so much anymore…

“You got a name, little guy?”

Sans clicked his teeth instead of responding to the human idling by the edge of the tank.

“I know a ‘yes, but go swim with bricks around your ankles’ when I hear it. Whelp, best know that the big wigs are already talking about what they’re gonna call you when they introduce you to the public. They’re fond of colors. Blue, Red, Crimson, Black, Gold...not very creative, eh? Think they’re deciding between Indigo and Cobalt. If you have a preference, say so now or forever hold your peace.”

Choices. Meaningless choices. 

He could give away the last thing he had left to him alone, that being his name, or he could covet it like a precious treasure. Either way, he doubted it’d make a difference.

“Cobalt has a certain ring to it,” Rus said, smiling.


	2. They say breathing gets easier when you're not alone

When Rus and Undyne (a female human with a shockingly red mane of hair) both approached the tank with those odd seal skins over their forms, Sans knew something was off. Blue swam cheerily around them as they plunged into the water, leaving Sans to wonder what was going on. What were they doing? 

“DON’T WORRY, FRIEND COBALT. THEY ONLY WISH TO HELP! YOU’LL FEEL SO MUCH BETTER WHEN YOU’RE OUT OF THAT FLOTATION HARNESS.” If they were freeing him of the device then why were they grabbing his tail? He snarled at the ripples of pain, thrashing helplessly in his entrapment. “HEY! EASY, EASY. IT’S OKAY. THEY’RE TRYING TO HELP.”

There was a PING and weight encompassed his Soul. Magic. Blue was attacking him? Sans wanted to thrash but the weight on his chest was paralyzing, rendering him helpless as the humans did as they pleased to his form. He clamped his sockets shut and fought the urge to despair or scream. Suddenly, he was released, and after an instinctive gulp of air, he sank, sockets opening as Blue pulled him to the surface. There was an odd weight on his tail. What? "A PROSTHETIC!" Sans, who thought himself familiar enough with these humans' language, had no idea what that meant. He flicked his tail up and goggled at the odd mass of white plastic that hung from him like an anchor. Were they trying to drown him now? Make him suffer by reminding him that he was too damaged to regenerate his flukes?

"IT'S A PROTOTYPE. YOU'LL BE FITTED FOR BETTER ONES AS YOU LEARN TO SWIM AGAIN AND THEY CAN GET PROPER MEASUREMENTS."

And just like that, Blue took him underwater again, and pulled him along. The humans watched in their seal skins, distant. Good. He probably would have bitten them if they tried to accost him further.

One would think relearning to swim would come easy.

It didn’t.

“Cobalt? You okay there?”

Sans floated listlessly at the top of the tank, perched upon one of the rafts Blue claimed was part of their “enrichment”. The other mer was clearly restless. There was only so much unresponsiveness a sociable creature like him could take before he sought out a different source, that being the humans working at this ‘rehabilitation center’. He rolled over, ignoring the ache of his ruined ribcage (a long, twisted scar ran across his sternum, hideous...not that he was especially attractive before). In the water hung his tail, false flukes heavy. 

“HE’S SAD. I THINK IF HE WASN’T COOPED UP IN HERE AND WAS WITH THE REST OF THE SCHOOL, HE’D BE HAPPIER.”

Rus shifted at the edge of the tank, likely leaning closer to Blue, “I know you mean well, bud, but I’m not sure if he’ll ever be ready. He’s...not recovering like the others.”

“TCH. THAT’S BECAUSE THE OTHERS HAD EACH OTHER.”

“He’s got you?”

“...Rus…”

“Right...right...you’re missin’ your pals too. But we can’t rush this. He’ll get seriously hurt if we do this wrong.”

“TRUST ME! I THINK HE’LL DO MUCH BETTER OUT OF THE SICK TANK AND WITH THE OTHERS. HIS INJURIES ARE AS HEALED AS THEY WILL GET UNLESS YOU HELP MEND HIS SOUL.”

“1 hp…”

Sans closed his eyes. Trying to ignore everything. Blue did his best to work with Sans in swimming, but he was so tired. So very, very tired. It was easier to just sit at the bottom of the tank and let the subtle current send him drifting, instead of fighting against the pain and the wrongness of the false flukes. Especially since he doubted the pain would ever go away. Cursed forever by _them_. 

A test run, the humans called it. The facility was closed to the public for the day, and his ‘handlers’ took it upon themselves to move Sans from the sick tank into a mostly outdoors enclosure. When was the last time he saw the sun? The enclosure paled in comparison to the mighty sea, but it was far vaster than where he was before, brimming with life. There were stones and sand and plants setting a rich backdrop of an array of fish. As they lowered him into the water, Blue popped up to greet him, eyelights especially large.

“I CAN’T WAIT FOR YOU TO MEET THE OTHERS! WE’RE GOING TO HAVE SO MUCH FUN! MWEHEHE.” Blue caught him around the middle and rolled them so that Sans laid across his back, able to cling to him like a whale calf who’d yet to take his first breath of air. Holding on was easier than causing a fuss by refusing, so he let his form mold against Blue’s, their bodies moving in unison as the overeager mer started swimming. The pain was normal enough by now. His agency and dignity all but nonexistent. He’d endure this...whether he wanted to or not.

Sans’ eyelids were drooping by the time Blue ducked deep into the water, darting into a cave that almost looked real. They surfaced against within it. The natural light dim, the air thick with humidity. A grotto. After so long of constant display, he’d almost forgotten the primal comfort that were enclosed stone walls safe from prying eyes and predation. He peered around and found his Soul beating a little quicker. Four other mers lounged in the shallows or on slick rock, all in possession of dangerous, warm-hued magic and pointed teeth. This was Blue’s school?!

The chatty mer dragged him to the shoreline and propped him on the sandless beach; after determining that Sans wasn't about to slip back into the water to drown himself, he clicked his teeth approvingly and splashed his way to the largest one, likely the leader. All of the mers were of skeletons like himself (the fleshy variety were less common and isolated strictly to the warmest waters), and possessed overt scars, crippling injuries on full display. The largest of them was littered with chips and cracks, like he was crushed in a collapsed tunnel, the left side of his skull marred with massive gouges, as if something tried to claw his socket apart. No light alit within the dark hollow. Likely blinded by the attack. His magic was a deep, violent red, with darker blooms where past trauma left its mark. 

And Blue was cuddled up to him like he didn’t have the teeth to dust them.

“like what’cher see, angelfish?”

Sans jerked back. The mer that had been sitting next to the large male was suddenly next to him, far too close, his tail pressed against Sans’, brows low and flirtatious. His magic was a far brighter shade than the other male’s, more akin to the odd writing around the tanks, or freshly spilt blood. Like DETERMINATION. He was also far smaller with thicker ribs and a lethal grin. Gold fangs glittered from the corner of his mouth, a crack snaking from the false teeth to his socket. But unlike the other mer, both of his eyelights were lit.

Brothers?

The flirty mer looped an arm around Sans’ shoulders, “sorry tah inform yer, but the cuddly lil dolphin yer been pal’in up wit is taken. ‘course he don’t mind sharin’, but boss will prolly hang yer upside down by yer flukes if yer get between ‘im and his mate during—”

“SHUT UP, RED! YOU ARE NEEDLESSLY TERRORIZING OUR NEW FAMILY MEMBER.”

Red—as the largest mer shouted—gave a careless shrug, “what? he wuz lookin’ at yer like yer wuz a fresh caught tuna. i’m helpin’.” He jabbed a thumb in his direction, “big, bad and bitey over there is boss. humans call ‘im crimson.” 

“UM, RED, I DON’T KNOW IF HE UNDERSTANDS WHAT YOU’RE SAYING. HE HASN’T SPOKEN ANY HUMAN WORDS SINCE WE’VE MET…” Blue said, flicking his tail, incapable of sitting still for long.

“tch,” Red made an amused noise. “oh, he understands us more than he lets on, dolphin. don’tcha?” His gaze was calculating. Not appreciating the lack of personal space or the expression on Red’s face, Sans growled, left eyelight flickering with warning. To his surprise, Red’s flickered in return, just twice, acknowledging and dismissing the threat. “yep. I know his type. lotsa magic. lotsa smarts. shitty huntin’ skills. prefers trappin’ shellfish and nibblin’ kelp over chasin’ down energetic prey or pickin’ fights. prolly has never tasted shark or gotten’ into a territory fight with another school.” He clicked his teeth. “am i right, angelfish?”

Sans didn’t deign to give an answer.

Instead he looked away at the other two mers, both of whom were watching in silence. There was another mer around blue’s size, his features sharper, eyelights verging on the cusp of maroon. He had thin facial scars like the other two but his magic was dark, its luminance almost nonexistent. It was impossible to tell the underlying hue, which left the distinct impression his magic flesh being black...which wasn’t normal. Behind him was the curled form of a mer far closer in size to Crimson than not, with sunset eyelights and a brilliant tail to match. If not for the false fangs on his top jaw, there was almost nothing amiss with his appearance.

_“M’lord, he’s staring…”_ murmured the larger mer in the low, melodic notes of pearlsong and silt.

_“Of course he is, mutt. I am a prime specimen! Let him look and admire perfection,”_ the smaller replied in kind.

Sans squinted. The dark mer and the sunset one possessed similar shaped tail flukes and sockets, but unlike the former, the latter had a mouthful of mixed teeth. A hybrid? Mers were social. It wasn’t uncommon for cross matings to occur, but he’d never met one that was so obviously a mix between a strict predator and one that wasn’t. Then again...Blue was apparently mate-paired with Crimson…

“the high-and-mighty barracuda over there likes to be called lord fer some reason, but he’ll respond to black, and his bro will answer to gold. black likes to mouth off, but he only picks fights wit boss. don’t get in the middle. only blue gets away wit it, and it’s cuz he’s our mediator and cute.”

“HEY! I’M NOT CUTE, I’M MAGNIFICENT!”

Red snorted and curled his tail a little more around Sans’, “yer adorable. and loud like a human. lucky fer boss, i prefer my mates to be the strong-and-silent type.” Sans decided enough was enough when a hand frisked up his spine, and summoned up mostly neglected magic to shove Red away by the Soul. Red yelped as he toppled over. Laughter springing up in the wake of indignation. “feisty. our pups are gonna be sparky lil shits.”

Pups?!

“RED! LANGUAGE! YOU SHOULDN’T USE SO MANY BAD WORDS.”

“WHELP! I TOLD YOU TO SHUT UP!”

Red snickered, clearly unphased by the pair’s unified shout, “yeah, yeah. i hear yer. so, yer got a name yer wanna share or are we gonna hafta call yer cobalt?” At Sans’ continued silence, he nodded, propping himself up, “yep. thought so. welcome to the rest of yer life. if yer here wit us...there aint no out. means they think that puttin’ yer back in the ocean is good as dustin’ yer here and now.”

Sans could see why Crimson, Red and Black were stuck here. In the deep sea, they were at a severe disadvantage with their injuries, and that was if they were with a school. Alone would be torment. But Gold and Blue? The fangs were false, but Gold didn’t look like he killed prey by biting them. And Blue was pristine. He’d never seen a healthier looking mer in his life. 

“i see the shells tumblin’ in yer skull. dolphin would have the worst of it on the outside. he wuz born into this life. he thinks and talks like a human. lucky fer him boss has a soft spot fer lost causes.”

Born...Sans scratched at his sternum. Unsettled. He didn’t like the thought of a pup being raised by human hands. Stripping them of instincts. Of their language. Why were these mers even considering a mating if it meant their offspring would be stuck in tanks for human entertainment! 

“oh don’t get pissy. the humans here know better now. blue’s a fluke. his ma was injured and dusted havin’ him when they tried rescuin’ her. and they didn’t know nothin’ ‘bout mers back then, so they didn’t know ‘bout how schools treat foundlings. their pups will be free and shit becuz something, something ethics board...i’m a bit hazy on the details.”

Sans noted the fragility of Blue’s smile as Red spoke. He clearly liked the idea of pups but no mer would enjoy their offspring being taken away to be raised by an unknown school. He wasn’t sure what made him ache more: pups never knowing the sea, or Blue losing every one of his offspring because he could never provide them all that they needed here in captivity. His ire settled on Crimson, deciding that the fault laid with him for courting Blue despite his utter ignorance to their ways.

As if taking pity on him, Blue broke away from Crimson to pry Sans from Red’s embrace, “WE SHOULD GO BACK UP. THAT WAY RUS AND UNDYNE KNOW YOU’RE OKAY.”

_“Tch, get off your tail and go help him, Mutt.”_

There was a splash in response to Black’s sharp command, and then, Gold popped up beside them, gathering Sans into his arms. Blue’s eyelights shaped into vivid starfish before he leapt out of sight, obviously delighted that his schoolmates accepted Sans into the fold so readily. Gold hummed softly. His whole presence a little nervous but soothing, his song like ebbing waves and a high noon sun. He must be a Nurse, Sans mentally sorted. A mer who tended pups and their mothers, and chose the nursery for a migrating school. It was easy to relax in his arms. And for once, feel safe. How long had it been since…?

Sans pressed his skull against Gold’s chest, sleep dragging him under.

The humans decided that “Cobalt” would make his debut at the start of the month.


	3. Is falling up any better?

“y’know, all them oodles of humans are out there waitin’ to get a peek at yer.”

Sans curled up tighter in a shallow pool in the grotto. Shivering. How did they do this every day? Just being lowered into the tank as that voice boomed an introduction, all those eyes upon him. All those human Souls so close. He clutched at his sternum, his sightless socket; his mutilated tail laid limp, those false flukes heavier than ever. An animal on display. An amusement. Something to be broken when the shiny and new rubbed away. 

Red, in all his tactlessness, sprawled over Sans, “a nap don’t seem like a bad idea. especially since it can be real exhaustin’ being out there. blue loves the attention. boss and black thrive wit all that energy and stress. gets their protective instincts all fed full up. gold...meh, i think he’d like to be here too, but he goes wherever black tells’im. i bet if yer tell the barracuda you’d like to steal his puppy for naptime he’d give’im over.”

A twist and a shove sends them both into deeper water, but Red is unphased. It’s rare that he stops talking, and he doesn’t seem to understand the concept of personal space. From what he’s seen, Sans isn’t the only victim of his persistent attention. He will pester Crimson until he chases him off with shouts and a flurry of bones (yet the largest mer never harmed him). He will sass Blue until he comes close enough to prank, usually dropping slugs or kelp into inconvenient crevices until Blue shrieked with offense. He bothers Black the least, but that was likely because whenever he nipped at his fins, the mer would pin him to the bottom of the tank with bones until someone came to free him. Usually Gold. Out of everyone, Gold tolerated him the easiest, or perhaps Red was less obnoxious with him, because if he wasn’t trying to nap on Sans, Red was cuddled up to Gold in a comfortable way that reminded Sans of the intimacy that proper school provided. 

“so cruel. yer don’t treat the dolphin this way.”

Sans clicked his teeth and slumped back into the tidepool, only for Red to cuddle up again. Noisy and needy. Sans didn’t bother lift his head when he heard the arrival of another mer. Given their quietness, he knew it had to be Gold. He poked and prodded, as if making sure that Sans’ injuries hadn’t worsened when he wasn’t looking, before dragging Sans onto his back. Red helped. Definitely a Nurse. Red, he wasn’t sure about, but there was no denying the role Gold once played for his school. And even the youngest of pups and the most weathered of elders knew better than to fight or fuss with a Nurse when it came to matters of maternity or wellness. 

Resigned to his fate, Sans hung limp as Gold brought him back into the deeper water; back into the view of the humans. Gold crooned until Sans relaxed and reluctantly, he peeked through the glass wall of his prison. He could see them. See their Souls. See their excitement and wonder. 

“You can’t heal if you hide from your fears and pain.” Gold swam them closer to the wall where a cluster of small children had their faces pressed to the glass. Sans flinched back, but Gold reached out a hesitant hand and laid it flat, the tiny human jumping with joy as their action being mirrored by the mer. _“...You won’t be hurt anymore...and you’re under no obligation to trust me...but…”_ Sans touched the glass. Nothing. Not even Gold’s gentleness would make this okay.

Would ever make HIM okay.

Life in the mismatched school was...different. He did his best to ignore the humans as much as possible, but they were almost always there, watching, in some capacity. His only escape was the grotto, and hiding in there too much brought on touching and talks about the state of his Soul. So he resigned himself to being out in the open, finding some relief in basking in the sunshine on one of those floating rafts. Blue would always insist he get exercise daily, since laziness wasn’t going to help him relearn to swim, and any attempts to ignore him would result in either Crimson or Black dragging him off. Edge he expected, Black...that was a surprise every time it happened. He barely spoke to Sans, but the moment Blue’s eyesockets got all watery, he was a menace. Strange.

Even stranger was how Blue let Black feed and groom him like they were Courting, not a blink of discomfort or reluctance. Then Crimson would show up and he would gladly swim into his arms. Weren’t he and Crimson mate-paired? He only ever saw this behavior in young Mers that hadn’t gone through a Season with a partner and were trying to determine who would help them make the best offspring. No wonder Black and Crimson fought...Blue was essentially toying with two very dominant Mers, one of which being the established Leader. Why were the others not informing him what he was doing?

“YOU ARE IMPROVING.”

Sans glanced up to see the subjects of his ponderings watching his ‘swim lessons’ with Blue. Crimson gave an approving nod, and Black tilted his skull up. 

_“Good to see you aren’t a completely useless waste of Blue’s time.”_

Blue wriggled between the two and held open his arms. It was humiliating being so helpless. Knowing he had an audience. He would rather sulk in the sand than comply with Blue’s wordless wish, but Sans found that his willpower was weaker than ever. It was easier to fight through the lethargy than deal with the consequences of resisting. So he pushed up off the rock he rested on, and with slow, aching pumps of his tail, he swam the short distance to settle in Blue’s embrace. 

“MWHEHE! YOU DID IT!”

Sans peered blearily at Black, who was staring at Sans’ tail. Not the prosthetic, but his tail. His magic wasn’t near as blindingly bright and perfect as Blue’s, but any monster could tell that his reserves ran deep, even half-empty as they were. Black ran a hand absently against a dull fin on his own hip before huffing and darting away, gone so quickly that it was almost hard to believe he was ever there.

As the weather grew cooler, the more attentive Red became. He was like a barnacle with how much he clung. Always cracking open shellfish for Sans or presenting chunks of mangled tuna. He once even brought one of the live fish that was housed with them in the tank and offered to kill and debone it for him if Sans wanted something extra fresh. Blue scolded him for that. Crimson found it hilarious because he actually cackled, teasing his brother for finally showing proper initiative. It took a slap between the sockets and a hiss to get some peace, but Red did leave him alone for one glorious morning in the sunshine.

Of course, that was when someone else had to bother him.

“You’re looking better, little buddy.” Sans gave Rus a surly stare and blew bubbles as a response. He was finally alone for more than a moment and now the humans were going to ruin it by existing. Rus at least had the decency to seem apologetic, “I...I just wanted to share some good news with you. Blue says you probably understand what I’m saying, even if you don’t talk, so hopefully he’s right...The authorities found your...owner? Er, yeah, not the right word. The person who hurt you. It’s this big investigation but the evidence is stacking up pretty big against them for illegal poaching and abuse of a protected species. I can’t believe someone so young would...Anyway, justice is being served. They won’t hurt anyone again. I thought you should know.”

Sans stared at Rus, unable to feel a single emotion for a Soulbeat; then, a tiny seed of anger built into an inferno that burned out as fast as it roared to life. He saw flashes of a knife. Of red. He tasted dust. Saw his brother collapse into foam. Felt steel on bone. Heard screaming, his screaming, and laughter. 

“Cobalt!”

Oh, that was him. He was laughing.

Rus was paler than ever, one hand reaching out like Sans was crumbling apart before him. Maybe he was. Maybe he couldn’t. Maybe he would. Maybe. Maybe. Maybe. Sans closed a hand over his non-corporeal throat, the rusted croak of neglected mana lines reminding him of how long it was since he vocalized more than a growl. 

“justice,” Sans rasped. “what a joke.”

He dove into the water, his brother’s memory chasing him all the way to the grotto.

_“Get up.”_

Black’s demand cut through the haze of Sans’ stupor. He remained curled up until Black literally picked up him and dove into the water with him in tow. Sans hissed and struggled, beating his fists ineffectively against the other mer’s back. Eventually, Black dropped him in a crowded corner of the tank that was mostly shielded from human eyes. Maroon eyelights glimmered with agitation, his aura crackling with ready magic, the kind that warned away the unwitting that he was ready to fight. Black was every inch a Hunter and Warrior. Smaller and faster than Crimson, with sheer audacity making up for his lack of physical strength. 

He formed a bone attack. 

Sans wondered if this was how he died.

He survived them. He endured surgery. He existed on 1 pitiful HP.

Black gripped the magic spear and lunged for him.

Sans clamped his eyes shut.

And felt abandoned instincts surge up, responding to the pressing threat with a howl and a snap. The bone never pierced his body. Sans peeked open is sockets and found Black pinned to the stoney wall, blood and mana leaking from fresh wounds. A smug smile on his skull. 

_“I was getting sick of your moping.”_ Black shrugged off Sans’ hold on his Soul and swam a tight ring around him. He huffed before darting away. Likely seeking out Gold to tend his injuries.

When Red presented him with a pearl, Sans could only shake his head in disbelief. Crimson and Blue were...occupied...in the privacy of the grotto, the cold weather bringing with it the desire to mate. Sans wasn’t unaffected. His traitorous body still went through its usual cycle with the seasons despite the relatively recent trauma, making his whole body itch. He avoided the worst of it in past seasons given his school was, well, a duo, and Papyrus had been too young to feel compelled to seek out a school with compatible mers. And Sans? He was social, like all mers, but any kind of parental urge was muted by his need to raise Papyrus. It would have been easier if they sought to join a proper school...but Sans had never known a large family (his school had been only a few more in numbers than just their parents) before he was practically thrust out into the deep blue on his own, a half-grown pup depending on him.

This was the first time he was stuck in close proximity to unrelated monsters. 

“...do yer really dislike me that much…?” Red closed his first around the pearl. Sans sighed and motioned towards Gold, who was quietly grooming Black’s spine. They knew each other longer and Gold was far more inclined towards cuddling up with Red than Sans. Red sank lower into the water, his eyelights dim. “gold aint gonna mate wit nobody till black has first. apparently it’s some kind of hierarchy bullshit from their old school. i wuz hopeful fer a while, since boss wasn’t interested much in blue fer years before they showed up...but it wuz like the moment black started eyeing up the dolphin, boss realized that he was pretty damn fond of the pipsqueak. not like black stood no chance against boss. he’s strong, but even blue wit his lack of any common sense or instincts knows that it’s not the best idea to mate someone that is terminal. heh. then yer showed up…”

Years. Sans felt the concept lodge itself in his skull like a parasite. He wasn’t ever getting out of here. Red was lonely. A mature mer in his reproductive prime that very clearly desired the intimacy of mateship. A lifebond partner. Someone to hold, protect and shelter with until he died. And the mer he wanted—needed—wouldn’t accept him in that fashion because his brother was unmated. A brother that was sick, so sick that it tainted his magic, even if he still acted healthy. It could be years before the illness dusted him (the humans were apparently rather adept at keeping things alive that don’t necessarily want to be). So Red turned his attention to Sans. Hopeful. 

“no.”

Red blinked. Whether he was stunned by the rejection or the fact that Sans spoke, Sans wasn’t certain, but the other mer swallowed and nodded his acceptance.


	4. Let's keep choking down oxygen.

_“Do you want something?”_

Black was stalking one of the larger fish released into their enclosure for the sole purpose of giving the mers prey to hunt. He had a spear in hand and instead of trapping the fish in a cage of bones, like he might in the open sea, he was following the fish around the tank, readying himself for the perfect killing strike. Sans’ presence spooked the live meal and left Black grumbling. 

“...clams…”

The reaction was instant. Black swung around, sockets narrowed at Sans as he floated idly, the current in the tank making him drift to the side. Black dispelled the spear and didn’t respond. Just watched. Sans expected him to snipe at him to stop being lazy and get his own food, but the other mer did no such thing. The cold water was affecting Black as much as the others and he was a provider by nature, in the same vein that Gold was a nurturer. 

Sans gave an easy grin and swam towards the surface, the prosthetic almost forgotten. Blue mentioned that he would be getting a permanent one soon. Lighter and better fitted to his swimming style. Far slower than he used to be even on his most sluggish days, Sans broke the surface and dragged himself onto a raft. His raft. If the others used it before, they didn’t anymore, because this was Sans’ favorite place to sunbathe. Even if it put him in perfect view of the humans. 

Sans was nodding off when a wet hand plastered onto his face, _"Wake up!”_

Black clicked his teeth and dumped a pilfered bucket of clams and other shellfish onto the raft. “YOU LITTLE PUNK! WHAT THE HELL ARE YOU UP TO?” Did he really steal the whole feeding bucket from Undyne? Sans tried to imagine Black asking nicely for a special snack, but it was quickly replaced with Black demanding clams because ‘you insufferable humans have to keep me happy’. 

_“What? Are you so incompetent you need me to crack them open for you too?”_

He shrugged, “sure.”

_“Next you’ll want me to feed you by hand.”_ Sans opened his jaws. The offer and challenge laid itself plain before Black. The other mer tensed but he cracked open a clam. His claws fished out the meaty insides...which he popped into his own mouth. _“Tch. Do it yourself.”_

_“Are you earnest or simply messing with my brother’s affections?”_

Sans twisted an unopened clam between his palms. The past few mornings were marked with Black waking him up from a dead sleep by dumping breakfast over Sans’ head. There were always clams. He wasn’t even especially fond of clams. But that single word, that lone mention, and Black provided. It took so little…

Gold pulled himself a little further onto Sans’ raft, looming, making full use of his size. He easily doubled Sans in length and weight.

To be honest, Sans knew what he was doing and why, but it wasn’t out of malice or even affection. Instead: practicality. If Black was courting Sans, then Red could court Gold, and then most everyone would be a little happier. Black would have a mate until whatever illness tainted his magic got the better of him, and Sans wouldn’t be worse for his loss. Hard to drop lower than a 1HP. He wasn’t even put off by the idea of loving Black in time, even it meant dusting when he was lost to the world. That was fine. It would all be fine.

Gold sighed and pressed his skull against Sans’. A silent plea to not hurt his brother.

The air and water continued to grow colder. Sans’ magic continued to itch. The humans accosted him again and fitted him with a new set of false flukes, these almost the same shade as his flesh, albeit lacking the radiance of his magic’s glow. And Black kept bringing him clams. So many clams. Sans was dozing in the humid warmth of the grotto when Black dropped his daily offering beside him. Urg. He rolled over, still full from yesterday’s meal. Warm season was for feeding; his appetite became sparse when the weather chilled. The constant meals left him feeling glutted, his reserves not only restored but overflowing. 

_“Eat,”_ Black demanded. Sans curled his tail to cover his head. A growl built low in the other mer’s chest as he loomed over Sans, pressing the clam against his teeth. Persistent. Disinterested in taking a single bite and wanting more sleep to stave off the constant itch in his magic, Sans flicked his new flukes, knocking the shellfish aside, the treat clattering across the stoney floor. He could easily pass a few days without touching food—though he supposed that might seem a little strange to leaner, more active mers that spent all their energy hunting. Sans thought Black understood his desires until he heard the scrape of bone on shell and the other mer muttering about picky, lazy mates.

Oh. No wonder Gold was concerned. Black was serious. Very serious. This wasn’t just a fleeting courtship to him, but a mating ritual. It was what Sans wanted, so that Red could be happy, but...he didn’t expect Black to, well, respond so readily to a simply request for food. He hadn’t even glowed his eyelights at him. Or lit his magic to Display. They hadn’t even groomed one another, though Gold kept Black’s bones meticulous and Blue wasn’t one to let anyone become grubby. Even Crimson once drug Sans onto his lap to pick sand from his prosthetic after noticing how dirty it became after a swimming lesson. Then again, it wasn’t as if Sans had asked or initiated anything further. Black was possibly waiting for him to make the next move, or thought Sans was the coy type. 

Suddenly, the gooey insides of the clam was pressed to his teeth. 

Black was feeding him? _“This was what you wanted from me. Go on. Take it.”_ Was Black embarrassed? Sans sat up, still not hungry but understanding his schoolmate a little more. He closed a hand over Black’s and took the clam meat, and held it to Black’s teeth in return. 

“i’m full, bud. thanks.”

He stared hard at Sans, before opening his jaws and accepting the morsel. An awkward moment passed, neither knowing quite what to do if Black couldn’t throw food at him, and the urge to nap lingered. Whelp. In for the oyster, in for the pearl. The two of them were alone in the grotto, so there was no harm in letting his overflowing reserves trickle to the surface, flooding behind his eyelights, and lighting along his false flesh. The dim cave filled with the faint luminance of his deep-blue magic. It wasn’t a bright or flashy color, but Black was enraptured regardless. The Display was brief, Sans growing weary quick (his stamina was never the best, Papyrus was the energetic one, Sans let the currents dictate his pace), and soon the grotto was no longer alight.

Sans yawned, “nap time.” And he lifted an arm, inviting Black to lay with him. To the surprise of the entire school, the pair was found curled up together later, fast asleep.

Snow. When was the last time Sans saw snow? He shivered as cold flakes littered his bones, not quite enough to squelch that burn within. Sans rolled over on his raft, tail submerged. Too cold but not cold enough. Every instinct screamed at him to migrate. To mate. To do anything to soothe inflamed magic. Both Red and Blue checked on him, earning snarls and hisses. This was his raft. His cold spot. And they weren’t going to—

—he averted that thought with a curl of his form and an unfortunate brush with friction. 

Dooming himself to discomfort until the Warm Season returned, Sans tried to sleep. This lasted up until he sensed another mer nearby. He hissed irritably. Crimson was unimpressed. He huffed and beached himself on a separate raft, a few deliberate flicks of the tail sending him careening into Sans’. “YOU BIT BLACK AND TERRORIZED THE OTHERS, ALL SINCE BREAKFAST. IMPRESSIVE,” Crimson said, his dry tone not lost on him. Right. He was especially crabby when he woke up, and when Black did his usual pushiness with the clams, Sans gave him a nip on the hand in reproach. The flawless and awe inspiring Malevolent Black was definitely not sulking. “FIRST RECEPTIVE SEASON?”

“fuck you.”

Crimson flicked Sans’ nasal bone, “LANGUAGE! YOU’VE SPOKEN TWO WHOLE WORDS TODAY AND ONE OF THEM WAS ONE OF THOSE HUMAN SWEARS. DON’T PICK UP RED’S BAD HABITS.” When Sans rolled over, he splashed him with cold water. “...IF YOU ASK, BLACK WOULD...HELP. THAT IS ONE OF THE PURPOSES OF A MATESHIP.”

“we’re not mates.”

“CHATTY TODAY, AREN’T WE? IF YOU ARE DISINTERESTED IN PROGRESSING YOUR RELATIONSHIP AT THIS TIME THEN I MUST BID YOU TO AT LEAST STOP BITING. THE HUMANS ALWAYS THROW A FUSS WHENEVER BLACK BLEEDS TOO MUCH, AND HE IS IN ABOUT AS COMPANIONABLE MOOD AS YOU.”

Blue’s buoyant energy made them both turn, “CRIMSON?”

The large mer slid off his raft, “THINK ABOUT WHAT I SAID.” 

The warm season was closer than it was far, but it was still cold. He loitered so much at the surface of the tank, near unconscious, just basking, that Rus ran a CHECK on him. He was healthier than ever, just with no proper outlet for his glutted reserves other than, well...making a souling. Sans hadn’t changed his opinion on that subject. He was settling in for another long day of snoozing when Black flipped his raft, dumping him into the water, sending him sputtering awake.

_“I require your complete attention.”_ Sans resurfaced, his annoyed look saying everything. Black had his attention, for worse or better. Black puffed his chest, _“Our acquaintanceship has not been an extensive one, but I’ve come to the conclusion that you are smitten with me, and it would be a grievous error to not voice my own feelings on this matter. Of course, it is easy to see why you would be enamoured by my greatness, so much so that you could barely bring yourself to test my interest in a mutually beneficial exchange by requesting nourishment. But as for how I feel…”_ Black clicked his teeth, faltering, a dull, pinkish flush rising to his skull. _“It would be remiss of me to claim that...I feel nothing. No, I feel greatly. It is likely more than you ever dreamed but you...I wish to…”_ If not for the rude awakening, Sans might have called this display cute. Black straightened his spine and grasped Sans’ hand, flattening a whole oyster into his palm. Sans’ Soul stuttered. He knew what was in the oyster.

Wasn’t this what he wanted ever since Red offered his own pearl?

_“I wish to extend to you the honor of being my mate.”_

It wasn’t even a full season since their ‘courtship’ started. Sans cracked open the oyster. Inside was, not one, but a cluster of pearls. Had Black gone to Rus and requested oysters until he found what he was looking for? Had he been saving this for some time? 

_“I see you are struck speechless!”_

Black’s voice was strained, body tense, expression open and expectant. What was he doing? It wasn’t right—

“...sure...i’ll be your mate.”

—but there were worse things than a mate you didn’t love. Sans’ own sire and dam were practical mers, coming together for companionship and reproduction, though he liked to think they cared about one another. This was the same thing. 

Sans swallowed as Black’s eyelights flooded his sockets like tiny moons trapped within a midnight tide. The tender moment faded all too quick before he was back to his posturing. Black wasn’t a bad mer. He’d make a good mate.


	5. Nothing is ever fair for us...

The return of warmer air and water marked the end of Sans’ persistent itchiness and desire to do little more than lay unconscious for days on end. Crimson wouldn’t leave Blue out of sight for longer than a blink (the potential of pups spurring instincts into a fury). Red spent even more time cuddled up to Gold, who now had more time to lay about with Black occupied. Speaking of whom...Sans squirmed, adjusting himself on the raft he shared with a certain someone. Black was an obsessively attentive mate. When he wasn’t patrolling the tank for nonexistent predators, he kept Sans in his sights, happy to play guard while Sans snoozed. A simple thing, touch. You never realized it was missing until you found it again, and your world felt fuller.

Not that Sans would admit as much. Nor would Black. No, the both of them were quite content to act as if cuddling up was a chore for Black, and that Sans would have been just as happy if anyone else was there in his place. 

_“you will practice swimming with gold today,”_ his mate announced. That was Sans’ only warning before the mercurial mer flipped the raft and dumped them both into the water. Why did he accept the jerk’s pearl, again?

“WE’RE HAVING PUPS!”

Sans had long since lost track of the days. Warm season was at its peak, making him anxious and hungry. So hungry. He didn’t need the reserves for migration, but his soul demanded energy, leaving him agitated. Black didn’t seem to mind the voracious appetite of his mate, and happily provided, a strange spark in his eyelight...said spark became more intense when Blue announced his “happy” news. 

He turned his gaze across the School. Blue was giddy, and behind him loomed a stoic Crimson. Red latched onto Gold and murmured something against his skull that made the larger mur’s magic flicker with surprise. And then there was Black. He stared hard at Blue with that indescribable intensity that couldn’t quite be called jealousy. No, if anything, it was best named longing. Sans’ Soul twisted. Nope. He couldn’t—wouldn’t—do it, for a multitude of reasons. As the others closed in to congratulate the pair, Sans slipped out of the grotto.

Had a year really passed since he arrived? The water was cooling, which brought along both memories and a familiar itch. Blue was utterly glowing with life, his sleek form bloated and cloudy with the growing pups, their souls visible specs. Crimson was impossible to pry away from him, though more than once Bue tried kicking him out of the makeshift nursery Gold and Red set up in the grotto. When the waters started to warm again, there would be pups. Captive bred and born pups. Pups that were better off if the humans took them from Blue when they were old enough and abandoned them with a wild school. It was an unfair situation. But the pair made their choice.  
Sans didn’t want to imagine Blue’s heartbreak when that day inevitably came around.

He was about to go back to the grotto when a hand caught his arm. Black. 

_“Unless you wish to be scarred for life, I suggest staying up here for now.”_ The disgusted look on his face told Sans everything he needed to know. Sans hid the urge to growl his frustration. Red and Gold knew better! Why would they risk making pups when they would just be— _“Tch. Don’t tell me...clams?”_

He blinked at his mate’s false annoyance. Black would poke out the eyelights of anyone who tried to claim he had a sense of humor, but the sharp-toothed mer had his moments. Since he accepted his courtship, he saw quite a few of these little moments, glimpses into who Black might have been before his world turned upside down. None of the mers liked talking about their pasts, of the schools they lost and the adventures they would never have again. As if subconsciously, they all understood that it was easier for them to pretend that there was no before, since this life was their only foreseeable future. 

Black dragged Sans along behind him to play look out. They hid amongst plants and false stone until Rus walked by the glass...then Black summoned a bone spear and shattered the thing against the side of the tank, visibly startling the human. Black snickered, smile wild and malicious. Rus gave an unamused look in return. Then Black motioned at Sans as if that meant something, earning an eye roll from the human. 

It wasn’t long before the pair of them were cracking open clams. 

Heh. Whenever Sans showed the slightest bit of moodiness, his mate tried to fix it with the food he used to court him. Honestly he was a little sick of the darn things. But the pride on Black’s face helped push away the ire and the looming sense of unease for the future.

_“I want one.”_

Sans stared at his mate, before letting his eyelights trail to where Blue sat at the edge of the tank, waving at humans, Crimson looking absolutely hostile. Apparently the tiny mer had a way of handling him, because he didn’t drag Blue away from the curious eyes of the visitors, or discourage him from chattering with them about the pup due come spring. Black crossed his arms before continuing, _“I understand your recentience given your fragile HP, but that is why I, the Malevolent and Generous Black, have decided to assure you that your health with not be endangered. For it will be I carrying our pups. After all, my HP is far superior.”_

“no.” Black winced, as if he didn’t expect that response. “that’s just the cold puttin’ ideas in your head.” 

_“Now would be an optimal time to procreate,”_ he argued. _“No doubt the mutt and that slavering sea urchin he’s mated with will conceive. And certainly their pup will be younger than Blue’s. But a pod of three pups would be—”_

“i said no, black. i told you before the cold season started, i’m not havin’ pups when i can’t...” When he couldn’t keep them. “and furthermore...what about your health? you don’t have the reserves to—” Sans caught himself when he noticed the change in Black’s posture. The way his hands curled against his dark ectoflesh. 

Terminal. They didn’t have a how or when, but for a mer that supposedly was interested in pups, Black was lean. Too lean. Slim with that haggard hunter physique, his last meal too long ago to remember clearly. There was a grey brittleness to his bones that he didn’t recall from the season prior. 

Black noted his gaze and bared his teeth. Without a word, he dove under the surface, dark flukes vanishing in a few flicks. 

It wasn’t long before familiar red-and-gold caught his attention. The typically occupied pair bore disgruntled expressions of being interrupted from far more pleasant activities. Red practically crawled onto Sans, groaning in exasperation as his weight drug them both down. Stronger and used to the prosthetic the humans fitted to his form, Sans wriggled them back up, and squirmed free, swatting Red’s with the false flukes as he splashed to a nearby raft. 

“cobaaaaaalt. yer need to go make stupid faces at black, he’s in one of his moods.”

“no.”

“no? fuuuuck, yer two ‘ave a fight or somethin’?”

When Sans didn’t respond, Red whined again, clearly no less needy for attention from the object of his affection than when he was unmated. Who would have guessed it of the toothy menace? From what little Sans gleaned of Red and Crimson’s culture from before they arrived here, their pods tended to be small, and offspring few, with Nurses being vicious defenders of their pups, and often the ones to carry young, meaning they were rare to assume a role outside of parenthood. It was strange for Sans to wrap his head around, but it rather explained why Crimson had no qualms with Blue’s utter lack of instincts. He was perfectly happy to do the hunting and fighting, while Blue took care of their children. Well...until the humans inevitably—

_“It seems my warnings to m’lord fell deaf,”_ Gold murmured, gathering up Red. His stare was hard. Sans felt a shiver crawl up his spine like an octopus on the prowl. 

“i guess so.”

With a heaviness in his chest weighing him down like a stone, Sans sought out his mate.

The conversation was distressingly quiet. There were too many reasons against consummating their mateship. But as they fell silent, Black growled and slammed his fist into the stone wall of the grotto, his emotions on rare display, _“It’s not fair.”_ Sans curled around the other mer, guilt returning for the first time in a long while.   
It wasn’t fair that Black was stuck in this tank.

It wasn’t fair that Black’s body would give out in his prime.

It wasn’t fair that they couldn’t give a proper life to any pups conceived.

It wasn’t fair that they couldn’t be normal mates.

...It wasn’t fair that Sans didn’t love Black, but accepted his pearl.

Black buried his face against Sans’ collarbone, their Souls dangerously close, heightened emotions and the chill of the water making them both shudder. “I don’t care if it kills me,” Black confessed, sharp and bitter. _“I don’t care if it means I do not get to live another five, ten, however many seasons these blasted humans think they can sustain me. Because they’ll be free. They will know the open ocean.”_

He saw a desperate final bid for freedom in his legacy. One that Sans wouldn’t give him.

“sorry…”

Black scoffed, _“Do not apologize to placate me.”_ He didn’t push Sans away. _“Perhaps it is indeed better this way. What sensible mer would wish to spawn with a mate with my...condition…”_ He clung tight, terrifyingly vulnerable.

All Sans had were muttered apologies. There was no one else. With Blue having chosen Crimson officially, and Red mated to Gold, it left the two of them, the most broken of the bunch, to cling to one another, seahorses adrift in the blinding deep without anchor, just waiting for the current to crush them against craggy stone. 

Violet and Lavender came into the world healthy and bright. It was obvious immediately that Violet took after their father more, with prominent fangs already peeking from their upper maw, and a long, thin body. Whereas Lavender was rounder, softer, and more vocal. This young it was impossible to know their gender, their bones still malleable, and Souls influenced by the environment. As they entered maturity, their skeletons would settle on a fixed form. However, like all monsters, land or sea-dwelling, it wouldn’t influence reproduction.

Gold was quick to gather with Blue away from prying eyes, clearly happy to be helping mind pups and their mothers. And if the way he kept herding Red to spend time in the nursery with Blue, the larger mer had news to share. This left Sans and Black apart, watching. 

_“Hmph. You need to eat,”_ Black announced, dragging Sans away. _“What would you do if I wasn’t here to take care of you? Spoiled. So spoiled.”_  
His Soul drummed a little faster. Since their moment in the grotto, Black and he spent much of the cold season wrapped together until they fell into comfortable silence. And even Sans wasn’t immune to bonding rituals. If they were to be alone, it was better to be alone together. However, what worried him was the lack of manic energy that once plagued the other. Last cold season he would have harpooned anyone that suggested he lay curled up in the sun for days on end. Now he napped. 

Sans gave a huff akin to laughter and nipped at Black’s neck, _“hurry up, m’lord.”_

Black flicked him between the brows before harassing the nearest uniformed human for clams. Sans was sick of clams. 

Yet he ate them without hesitation.


	6. I'm breathing in water, is that okay?

Orange, Sans decided, was a terrible name. Even if it was accurate. So terrible, in fact, he actually spoke to Rus about submitting anything else at all to those stupid humans that decided they had business in naming mers. 

“You could tell us their actual name?” Rus drawled. He said as much last time when neither Blue or Crimson would part with what they were personally calling their pups. 

“nah, why break your theme? i mean, colors, they’re super great.”

“How has Black not eaten you with that snarky attitude of yours?”

“i’m cute,” Sans quipped, well aware that in a normal School, he would be considered the farthest thing from attractive. His mangled ribs had long since healed into a pitiful mess he did his best to ignore, and discolored stains marred the flesh of his ruined tail. “now about red and gold’s pup…”

In the end, they announced the newest addition to the school as Copper.

Copper came sooner than the twins. The other pups weren’t even a year old when the hyperactive youngling joined the world. He had a mouthful of teeth that Sans could only describe as a surprisingly functional wreck (Gold explained he had the same issue when younger, until his magic settled and he lost the extra ones he didn’t need), and an eelishly scrawny frame that gave him a strung out appearance. In short, he was frightfully hideous. His parents adored him. 

_“Hybrids usually go through this phase,”_ Black stated with a shrug. Sans’ dubious stare and motion at the perfectly normal looking twins earned a scoff. Usually didn’t mean always. But neither Gold or Black seemed concerned. Then again, why would they be if this was how Gold looked as a pup? He did, indeed, grow out of it.

It would be a couple years before the pups would be mature enough to be separated from their parents. Slow growing as they were, each would be ready for release into the wild at about three. Rus occasionally talked about the school they were tracking and believed would make a good fit for the pups when the time came. No longer dependent on parental care, they would be taught to hunt, fight and all the other proper skills that a mature mer should know. Skills that Blue picked up in second-hand pieces but still didn’t quite understand. They could teach him songs and language, but not how to properly react to predators that don’t exist for him. Nor could they teach the subtle nuances of mer body language and signals that pups gleaned through their parents and schoolmates. 

(Sans thought back on Papyrus. He had to admit he did his best for him, but raising him mostly alone left the other mer a little odd, but that was fine. He was friendly and would have fit in fine and made a great mate to some nice—)

“DID YOU ROLL IN THE SAND?” Crimson drug Sans out of his thought while simultaneously pulling Sans onto his lap. Apparently he was banished from the nursery and needed someone to fuss over. Sans went limp as the larger mer manhandled him, grooming grains away from cracked bone and the crevices of his prosthetic. He wasn’t all that dirty. Black wouldn’t tolerate cuddling up with him if doing so resulting in a sand bath. But Sans offered no protest, letting their Leader busy his hands with ritualistic grooming. 

It happened one bitterly cold evening. The winds outside were fierce, the water frigid. Nothing the mers couldn’t tolerate, in fact, Sans recalled spending time colder. But when he woke up from his nap in the grotto, Black was cool against him. Not warm with thrumming magic, but cool. He shook his mate. Splashed him with water. Anything he could think of to rouse him. Black remained limp and still, breathing shallow. Sans CHECK’ed him, hoping it was nothing, that he was overreacting. What he saw had him screeching for Rus. For Undyne. For anyone! 

Black was Falling.

They transferred Sans into the recovery tank three days later, a weak but alive Black coiled at the bottom, crammed into a corner as if desperate to hide his pitiful state from the world. Hard to do when you were stuck in a transparent glass box. Sans forgot how small this tank was after so long away. How did Blue not start rattling shells from his skull after being stuck with him all that time? Full circle, he supposed. Once a patient, now the nurse. Unless this was supposed to be their way of letting him say goodbye. 

Sans swam to Black’s side and took up the role of fussy mate. He was tired. The water too warm and Black too still. 

“sleepin’? when did you become the lazy one? that’s my job,” with a dry chuckle he scooped the unresisting mer from the tank bottom, dragging them both slowly to the surface. A CHECK assure him that Black wasn’t actively Falling anymore, but his HP was low. Dangerously low. He positioned his mate along his back, like a whale calf that had yet to take its first breath. Sans could feel his Soulbeat this way. Swallowing and without an idea of what else to do, he let a hum build in his ribcage. The sound rolled and vibrated until it spilt from his false throat as an achingly rare song. 

It wasn’t the melodic tones of silt and pearlsong that made mermish language. Nor the squabble of seabirds and crashing waves. It was longing and grief, the bitter isolation of glaciers. It was temptation and pleading as warm as seal blood on a tropical current. (Come home. Be mine. Never leave.) Seafoam against the hull of a ship. The dragging lull of sinking deeper and deeper, darkness closing in, no fighting remaining. Rusted anchors lodged in sand. (Never go. Never go. Let me go with you.)

He sang until he lost his breath, bones trembling from exhaustion. He hadn’t sang like that since Papyrus’ death. He couldn’t. Because of them. 

“Siren.”

Sans glanced to the side of the tank, unaware of how long he had an audience. At the edge was Rus, brown eyes wide with something akin to wonder paired with pain. He huffed and narrowed his sockets at the trespass, curling his frame defensively around Black. Siren was a human word, one he learned to loathe when he was a pup at his mother’s hip, when she told him stories of sailors and slaughter. All mers were gifted with song. But only a rare few were graced with Song. Red wasn’t wrong when he accessed Sans at their first meeting, about Sans not being a hunter. About him relying on cleverness and picking up the languages of the humans just fine. Because why would he chase down prey when he could lure it to him with his voice alone?

He bared his teeth at Rus, magic swelling within his functional socket, a growl replacing music. The human held up his hands in surrender, “Easy bud. Not gonna hurt you...just, was surprised is all. I knew sirens existed, but I never…” The click of teeth silenced any further placation. Rus ran a hand through sandy locks, “Right. Right. You’re worried about your mate, and here I am intruding...I wanted to, uh, well, talk to you. You prolly know better than me that Black is...sick.” Too cool bones threatened to crumble at the most delicate touch. Darkened ecto that lost most of its scant maroon undertones. A Soul too dim to pierce the semi-transparent flesh covering his ribcage. Yes, he knew perfectly well how sick Black was right now. “We stabilized him, but his magic is breaking down. With regular transfusions, he may get another year or two but…”

But that depended on Black’s will to live through it.

“I’m sorry Cobalt.”

Death was a part of the natural cycle. It came for them all eventually. He knew from day one Black was terminal. However, that didn’t make it any easier to see his sharp decline. His strong, mouthy mate was supposed to sass him for another few years. He was supposed to shove clams at him for another couple warm seasons. He wasn’t supposed to go this soon! Sans clung tight to Black, a painful realization pinching the core of his being. Love. He loved Black. He loved the dying mer in his arms. 

“...let him go.”

“What?”

“let him go. let him back to the sea.”

“He will suffer needlessly if we do that. He can’t fight. He won’t be able to hunt. He’ll Dust within days in pain!”

“we are living, sentient monsters that you’re keeping trapped like animals! we should have the choice of where we die!”

“Cobalt…”

“sans.”

“What?”

“my name is sans. use it, human.”

_“Sans, eh?” Both Rus and Sans froze at the sound of Black’s croak. A weak, magenta eyelight flickered up at Sans, _“What has the pitiful slug done to earn your name?”__

_  
_

He cast a pleading look at Rus, who crumpled as he stepped away from the tank. For the first time in a long time, Sans felt the weight of his singular HP dragging him down.

The days marched on, Sans’ emotions an absolute mess. Black luckily tolerated his newfound clinginess with astounding grace, with a pronouncement that Sans had finally come to worship him as he so rightly deserved. Both of them ignored the pressing awareness of their own demise. 

It was late and dark, the warm water irritating Sans to no end, keeping him from proper sleep, when Black curled his form around Sans’, very much awake. There wasn’t much in the way of privacy in this place. But riled magic and raw instincts pushed delicate sensibilities aside. Sans rolled them both so Black laid stretched above him. When did his mate become so...small? He always seemed larger than life, all venom and violence. 

There were no questions of futures. Of rights or wrongs. 

For a night they were both selfish, in need of a reason to live. 

“Let me go." 

Sans wasn’t sure if Black was talking to Rus or himself as he waved away the human. He was there to give the magic transfusion. When Rus went to protest, Black hissed, all teeth on display. Rus’ shoulders fell, and he nodded. There existed so little agency for them in this place. When Rus vanished from sight, Black went limp in Sans’ arms, obviously over exerted. 

_“Wipe that stupid expression off your face,”_ he snarled. _“You look pathetic, and no mate to the Malevolent Black is anything less than magnificent.”_

“i’m not… 

_“Do I sound like i care about your opinion on your own worth? I chose you.”_

“...i used you…” Sans choked on the confession.

_“I am aware of your manipulations,”_ Black retorted. _“Red’s pining over that Mutt was obvious, but neither would act because of Gold’s ridiculous sense of loyalty.” There was affection intermixed with an ache. “It is my fault he is stuck here. My fault he was mateless and miserable.”_ He raked his phalanges harmlessly across Sans’ bones. _“...So don’t pity me, Sans. Pity yourself if you must, but don’t pity me.”_

“heh...so we were both being _shell-fish_?” Black pulled a face, but didn’t correct him. Sans dropped his skull against his collarbone. “i wish you could see the ocean again, one last time.”

_“I don’t.”_

“What?”

_“You heard me, numbskull,”_ Black snapped. _“Now make me a promise.”_

“...a promise?”

_“When given the choice to breathe or drown...breathe.”_

As the season started to warm again, Sans sensed it. It was time. He convinced the humans to return them to the main tank, to close their ‘exhibit’ from the public for the day. With extreme gentleness, Sans guided Black back to the awaiting school. Curious eyelights peeked around their parents, but all seemed to understand. 

Crimson began barking orders, and soon, all were gathered in the grotto, the children tucked away as the adults circled one of their own. They kept vigil for the next three days and nights. Not allowing the humans to intrude. It wasn’t until dawn the fourth day that Sans emerged with a tightly clasped clamshell and a request.

“return him to the sea.”

Rus and Undyne could hardly deny the demand.

That night, Sans Sang. Wondering the whole time how his Soul didn’t shatter into pieces and return him to the very same seafoam as his lost mate. He had a singular HP. Mers were rare to persist when their beloved fell like sand through their fingers. Yet here he remained. Breathing.


	7. I'm still here

For a manic few months, Sans kept an eye on his Soul, on his body. He checked himself over again-and-again for a trace of something. A reminder. But as the season turned hot, he knew that their singular mating did not culminate into a new life. No legacy left behind. No pups to know freedom in his wake. Nothing. The day the realization hit, Sans curled at the bottom of the tank and stayed there, guilt and yearning twisting up grief until the wound felt fresh again. Gone. Black was gone. He lived on only in memory because Sans was too self—

Arms wrapped around his middle and forced him to surface. Air hit his Soul in gasps and gulps. Sans knew immediately that it was Blue. “YOU’RE COVERED IN FILTH,” Blue chided, saying nothing about what Sans tried to do. Instead he settled them both on Sans’ favorite raft and began to pick between vertebrae, swift and familiar. Sans’ lids fluttered shut, memories of when he first arrived at the facility washing over him. He was angry but hopeless, then, resigned to his fate with a passive nihilism that nothing he did mattered. Heavy and once again helpless to the crushing weight enclosed around his Soul, he was a pliant clump of kelp in Blue’s arms. 

Fastidious hands plucked away every errant grain, cleaned and polished until both flesh and bone gleamed. Then he curled around Sans in a manner that was far too intimate. They weren’t mates. They weren’t pups. They…

He clung to Blue as if the mer was driftwood after a storm. 

It was like this the others found them. 

They took turns watching over him after his breakdown. Every day they made sure he ate at least once and kept him cleaned up. Eventually, motivation returned, slow and glacial, and Sans found his way into the nursery. He was no Nurse, but Gold seemed content to let him play guardian. Violet, Lavender and Copper were all too happy to clamber over Sans, clinging to the lethargic mer as he floated in the water. It wouldn’t be too many years before they would all be gone, taken to a foreign school to be raised in the open ocean as foundlings. They would be too young to remember their parents by the time they came of maturity. As far as they would know, they were orphans. 

He couldn’t in good conscious want to keep them. No matter how happy Blue seemed, it wasn’t right. Not when they had a chance to live full, proper lives.  
(Sans wondered how many pups the others would lose before they refused to let go of any more.)

With time came healing. Routine did not wash away loss, but it soothed the open wounds of grief. The others never left him to despair. Every night Red would drag Sans close to cuddle, and he’d wake to Gold wrapped around them, Copper latched onto his chest. Crimson would organize the morning ‘hunt’ and monitor Sans to make sure he actually ate. More often than not, Blue was the one who would instigate grooming, though the others would occasionally drag him to their sides to make sure he wasn’t picking up grime. He would spend the day either sleeping in the sun, or half-heartedly chasing the pups around the tank until they had mercy on him and decided to take a nap instead. Gold would usher them to the nursery before dark, and the cycle would begin again.

What he wasn’t expecting was for the cold to agitate his magic.

Sans fully expected to pass this Season without issue. His mate was gone. The others were paired off. Heh. Maybe he was just broken? He wanted the cold to go away! He didn’t want his body reminding him of the pups he’d never have with the partner that dusted a year ago. He needed it to STOP. 

“YOU NEED HELP?” Sans sucked in a sharp breath, startled by Blue popping out of the water to peer at him. He was on his raft. Everyone knew to leave him alone as he basked. Discomfort turned into hostility, and Sans hissed, flicking his tail at the other mer. Of course, the socially inept mer only blinked in response, those bright eyelights of his even more vivid than normal. Blue’s whole form was brighter than usual as if he were Displaying. Had Crimson honestly never explained to Blue what that meant? A growl low in his chest, Sans tried to stare Blue down, but only received a grin in return. “AH, YOU’RE TRYING TO BE BIG AND SCARY.”

Suddenly, he was no longer alone, Blue’s brilliant form bright as he sprawled astride him. Blunt teeth nipped at his collarbone. Sans shoved him artlessly back into the water with a splash. Blue laughed, tail flinging up droplets of water into air, a cascade of shattered rainbows showering down upon them. There was no mistaking the flirty implications of his actions.

“that wasn’t funny,” he snapped. “you can’t do that.”

“WHY NOT?” Blue at least sobered enough to look a little less impish.

“one, you’re mated. two, i’m not gettin’ between you and crimson. and three, not interested!” 

“DO YOU NOT LIKE ME?”

“blue…”

The other mer propped his elbows on the raft, his eyelights pulsing a hint, “I LIKE YOU.” Sans prepared to smack Blue for his idiocy when Blue curled his perfect flukes around his tail, sending a shudder through him. He hated cold season. So, so much. “CRIMSON DOESN’T MIND. HE KNOWS MY FEELINGS.”

“feelings,” Sans deadpanned.

Blue huffed, “I’M NOT LIKE YOU ALL. I KNOW IT. IT’S OBVIOUS. I WASN’T RAISED BY A MATEPAIR AND RUS ALWAYS TOLD ME THAT MONSTERS CAN LOVE MORE THAN ONE MONSTER AT A TIME WHEN I ASKED HIM ABOUT MATING RITUALS.” Of course he did. Because he wasn’t a monster. He was a human and humans were weird. “IF YOU NEVER CAME HERE...I WAS GOING TO ASK BLACK IF HE WANTED TO BE WITH ME. CRIMSON WANTED AT LEAST ONE SEASON JUST US...AND THEN YOU CAME, AND YOU TWO COURTED. SO I LET MY FEELINGS FOR HIM GO.”

“heh. and now you ‘like’ me? you’re hilarious.”

“I ALWAYS LIKED YOU. I LIKE ALL OF YOU. BUT RED AND GOLD? THEY DON’T NEED ME. NOT LIKE YOU. AND IT DOESN’T HAVE TO BE FOREVER, BUT...YOU SHOULDN’T HAVE TO BE ALONE IF YOU DON’T WANT TO BE.”

“this is tactless, even for you.”

“THE OFFER STANDS.” And with that, Blue vanished beneath the surface, leaving Sans alone with the roar of his thoughts.

“what crawled up yer pelvis and died?”

Red had the good sense to flinch at his own words before he bore his fangs at Sans, eyelights bright with ire. He went to pull Sans into their now routine sleeping arrangement when he bit him, something he hadn’t done since mating Black. Mana-rich blood dripped from his cracked palm and stained Sans’ teeth. Red flicked his wrist and turned Sans’ Soul blue, pinning him to the wall of the grotto in retaliation. 

“WHELP! WHAT ARE YOU DOING?”

“hey! i’m the one fuckin’ bleedin’ here.”

“LANGUAGE!”

“nobody asked you, dolphin.”

_“You shouldn’t be doing that in your condition.”_

“not you too, gold,” Red groaned and dropped Sans, crossing his arms with a glare at his mate. “also, it’s too early to tell. so leave off.”

“Brother?” Copper chirped from the nursery, head peeking up over the edge of the shallow, raised pool. “Having brother?”

“maybe, sharkbite,” Red mumbled, his anger smothered out. With the entire school awake and watching them, Sans wriggled with discomfort before slipping into the water. Maybe he’d go back once the others were asleep. He emerged beneath a cloudy sky, the moon and stars obscured, drenching the world in darkness. In the distance, he saw spots of unnatural light, the glow of human and land-dwelling monster settlements. It was loud. Terribly loud even in the quiet of night. He’d grown used to the noise, but in moments like these he wanted to cover his skull to just block out the cacophony. 

Sans floated on his back and traced the hazy edges in the sky with a phalange, his wrist limp, as if he could brush the clouds aside if he decided to put in some effort. His arm dropped to his chest. He would need to apologize to Red eventually. He didn’t actually do anything to deserve being bitten. 

“Care to explain yourself?” Crimson’s narrow  
eyelights pierced the dark like spears, his voice just as sharp, but words quieter than normal. One might even call it a reasonable volume. 

“nope.”

“I see. Might this have to do with Blue’s proposition earlier?”

Sans sat up, his form sinking until only his sockets were above the water, “you know?”

“Of course I do!” Crimson didn’t touch Sans. He didn’t move even a hint closer. He merely gazed at him, stare assessing. “We have an agreement.”

“heh, sorry, not biting that hook.”

“Oh? Why not? You obtain relief for the Season, and he gets to...expand his horizons.”

“thought your brother said you were the jealous type.”

“I am. Any offspring will be mine.”

“tch. i’m the one with the excess reserves, not mr. slim-and-trim fins.” 

“I will repeat myself since you appear to have coral in your skull impairing your ability to think critically,”  
Crimson drawled. “Any. Offspring. Will be. Mine.” He cocked his head. “Understand?”

Sans’ sockets widened as what the other mer implied settled into the cracks-and-crevices of his mind. Accepting Blue’s offer meant taking care to avoid creating a pup, but if Crimson wasn’t being a possessive terror, then it was entirely possible that either Blue wasn’t receptive yet after having the twins, or was already expecting. Given how Crimson wasn’t trying to hide Blue from the world, Sans reasoned the former was more likely. Meaning that Blue couldn’t create pups with a different mate right now even if he wanted to. It was ‘safe’ for him to frisk Sans’ bones. 

But Crimson...he was receptive. There was a twitchiness to his form and Soul. He could give Sans pups...but—

“i don’t want another mate.” He couldn’t even say aloud that he didn’t want pups. He just...he wanted Black back. 

“That is fine. If you change your mind, speak with Blue.”

Before Crimson could swim away, Sans whispered, “what do you get out of this?”

He shrugged, “A happy mate. Possibly two. Do try to avoid biting Red again, or Gold might rearrange your teeth.” Then he was gone, and Sans alone once more.

He was tired of being alone.

“crab.”

“WHAT? DID YOU SAY SOMETHING?” Blue peered over his shoulder, having been interacting with guests through the glass wall of the tank. Sans shot him a sullen stare.

“i want crab.”

He felt bloated and itchy, but if he had to choke down food, he’d rather it not be clams. Crab was the first food Blue fed him. It suited the occasion. Blue’s eyelights quivered with confusion, before shaping into starfish. 

“I CAN DO THAT! I CAN GET YOU A CRAB!” With a shout of victory, Blue swam off, calling to Rus until he brought over what he required. Soon the excitable mer floated across from Sans, gift in hand. Sans didn’t reach out to take it. “WANT ME TO FEED YOU?” He was so unlike Black, yet...similar. The need to provide a powerful drive. Sans gave a tiny nod and then Blue started snapping off legs and cracking open the carapace. Clumps of crab meat dangled from his fingers, the offering clumsy but earnest.

He could feel the curious eyes of the others.

Sans blocked out everything but the taste of crab. 

The first time he woke with Blue wrapped around him was strange. 

The first time he let Blue pull their hips together was even stranger.

The first time they consummated their mating was the strangest. 

The entire time, Crimson watched on. 

Sans thought that when the water warmed, their arrangement would end. But Blue kept snuggling up to him, whining when Red got to him first during naptime first. Crimson would always click his teeth at Red, who would huff about bossy brothers before curling up with Gold. 

_“Are you happy?”_  
Gold and Sans were alone together in the nursery, watching over the pups. The twins were almost old enough to be taken away, though it was possible all three would be removed at once to help them adapt to their new life. Copper was maturing faster than the twins. They wouldn’t be too far apart in growth when the day arrived. 

Sans blinked up at the large mer who had once been devoted, body and soul, to his brother, his loyalty so great that he refused to take on a mate until his brother did first. Not because Black was imposing some hierarchy nonsense as he led Red to believe. “i dunno how to answer that.” He swallowed.

_“Honestly.”_

“my body is permanently maimed by a human child that supposedly saw justice for what they did to me. whatever that is worth. i will never see the ocean again. i will die in this place...“ He drew in a shuddering breath, “i miss him,” Sans confessed in a whisper. “every day, i miss him. i wish i dusted with him.”

_“But you didn’t.”_

“no.”

_“So you moved on.”_

“he made me promise...he made me promise that if given a choice to drown or breathe, that i would breathe. so here i am, still breathing.”

Gold moved closer to Sans and pressed his forehead against Sans’, _“He loved you. He would have preferred you to move on than crumble in grief.”_

“why don’t you hate me?”

_“Because you made him happy. Despite my best efforts over the years...You’re the only one who ever managed that.”_

One early morning Sans uncovered the oyster Black gave him as a mating gift, filled up with those little pearls. He smoothed his phalanges over the surface of the shell and held it close to his sternum. He stared at the painted hues dancing along the horizon, as vibrant as the reef. If he strained, he swore he could hear the pulse of the ocean in the distance beneath all the noise.

“hey papyrus, it’s been a long time,” he began. “could you do me a favor and look after someone for me?”

**Notes for the Chapter:**

> -FIN-
> 
> Thank you for reading. This is all she wrote.
> 
> Have questions about this fic? For its characters? I have a holiday ask this year! Check it out @Catsitta on Tumblr. [Ask me questions.](https://catsitta.tumblr.com/page/2)
> 
> AUTHOR NOTES:  
> +This was originally supposed to be 5k oneshot Blue/Sans fic
> 
> +Black at one point was plotted to dust trying to carry a pup to term, and actually lived longer, having worn down Sans' objections.


End file.
